Highly Selective Ethanol Sensors Based on Co-Doped SnO₂ Nanoparticles Modified Bimetallic CoMn-Functionalized Metal Oxide Nanotetrapod Chemiresistors

Material modification techniques are pivotal for improving the material performance. In this study, the gas-sensing attributes of materials were enhanced through the modification of bimetallic Co@Mn-codoped ZnO nanotetrapods (ZnO(Co@Mn)) using transition metal Co-doped SnO2 nanoparticles (SnO2(Co)). Gas-sensing tests showed that SnO2(Co)/ZnO(Co@Mn) nanocomposites exhibited superior performance, including high response, low operating temperature, high selectivity, and short response/recovery times. At the temperature of 280 °C, the gas sensor based on SnO2(Co)/ZnO(Co@Mn) nanocomposites demonstrates an impressive response intensity of 204.6 to 200 ppm of ethanol gas. This highlights the sensor’s ability to operate at a lower temperature while maintaining excellent stability. The response time and recovery time to 200 ppm ethanol gas were quantified as 18 and 20 s, respectively. Comparing with pure SnO2(Co) and ZnO(Co@Mn), respectively, the enhanced gas-sensing performances of the SnO2(Co)/ZnO(Co@ Mn) nanocomposites are mainly ascribed to the heterojunction generated from the hybrid of ZnO(Co@Mn) nanotetrapods with SnO2(Co) nanoparticles, which not only improved the response and selectivity to ethanol gas but also reduced the operating temperature.